A.1 Major Changes Between V7 and SVR3.1

The awk language evolved considerably between the release of
Version 7 Unix (1978) and the new version that was first made generally available in
System V Release 3.1 (1987). This section summarizes the changes, with
cross-references to further details:

The escape sequences ‘\b’, ‘\f’, and ‘\r’
(see section Escape Sequences).
(Some vendors have updated their old versions of awk to
recognize ‘\b’, ‘\f’, and ‘\r’, but this is not
something you can rely on.)